Problem with NumberFormatException

Question

hi guys,
below is the codes that catches NumberFormatException
basically i want to read an int from file number.txt
can anyone help me?
thanks
import java.io.*;
import java.util.*;
import java.text.*;
public class Test
     String id = null;
     GregorianCalendar today = new GregorianCalendar();
     DecimalFormat df1 = new DecimalFormat("00");
     DecimalFormat df2 = new DecimalFormat("00000000");
     public Test(){}
     public String generateID()throws IOException{
          try{
               BufferedReader read = new BufferedReader(new FileReader("number.txt"));
               //PrintWriter write = new PrintWriter(new FileOutputStream("number.txt"));
               int num = 0;
               Integer year = new Integer(today.get(Calendar.YEAR));
               Integer month = new Integer(today.get(Calendar.MONTH)+1);
               String tempYear = year.toString();
               String tempId = tempYear.substring(2)+df1.format(month);
               String line = read.readLine();
               while(read != null){
                    num = Integer.parseInt(line);
                    line = read.readLine();
               num++;
               id = tempId+df2.format(num);
               //write.println(""+num);
          catch(FileNotFoundException ex){
               System.out.println("File not found");
          catch(IOException e){
               System.out.println("Error in reading file");
          catch(Exception ec){
               System.out.println("Error here");
          //write.close();
          return id;          
     public static void main(String[] args)throws IOException{
          Test t = new Test();
          System.out.println(t.generateID());

Answer 1

These linesString line = read.readLine();
while(read != null) {
  num = Integer.parseInt(line);
  line = read.readLine();
num++;are going to read lines from a file and convert them to integers until it can't read any more. You will get the last value from the file... unless the last line (or any line) is blank or contains garbage parseInt can't handle.
All the programs I have written usually read a number, then do something with it.
If you just want to read one line, take the while loop off.
if you want to trap the error, put a try/catch block around it.